The present invention relates to an apparatus for converting a rotational movement into a reciprocating lifting movement or vice versa.
A known apparatus of this kind (U.S. Pat. No. 2,246,733) can be used for controlling valves, robots, machien tools, or the like, and so as to avoid having to use crank-type drives in conjunction with pumps, internal-combustion engines, and the like. In these drives, each force-transfer system consists of individual drive balls that are arranged in part within the bearing drilling and are supported in part in the first and second guide grooves. For this reason, either the wall sections taht incorporate the bearing drillings must be comparatively thin or the diameter of the driver balls must be comparatively large in order that said drive balls can protrude to a sufficient depth into the first and second guide grooves, which leads to unfavourable mechanical/design conditions. Above all, however, because of the fact that the driver balls interact with both guide grooves by sliding friction, an apparatus of this kind is of only limited use and is distinguished by large frictional forces and a high degree of wear.